Boom



M. ARMSTRONG BOOM 2 Sheets-Sheet 1 Filed Nov. 8, 1947 I U Q Q N N.fizI/ezzfor Mei (If/77 fimszrory d y zYorzzeys March 20,1951 MARMSTRONG 2,545,937

BOOM

Filed Nov'. 8, 1947 2 Sheets-Sheet 2 Patented Mar. 20, 1951 UNITEDSTATES PATENT OFFICE BOOM I Merwin Armstrong, Hinsdale, ApplicationNovember 8, 1947, Serial No. 7 84,813

cables. The cables are normally swung free from the outer free end ofthe boom and are spaced upright some distance away from this first pointof attachment. Across this relatively long span :"the cables normallysag considerably and during operation of the machine the'cables arecaused to'whip due to the taking up .of the slack upon application ofthe load. This whipping of the cable results in the bouncingaround ofthe heavy boom, subjecting both the boom'and the cable to iexcessivemovement resulting in damage requiring frequent replacement of cables.

In the device forming the subject matter of the present invention theboom is designed to support the cable throughout substantially itsentire length so as to .eliminatesag in the cable, with the result thatthere is no bouncing of the boom vwith changing load conditions duringoperation of the machine. The life of the cables and the boom parts isthereby greatly increased and this 'is accomplished in a relativelysimple and yet effective manner, and the weight of the boom structure isreduced substantially below that of the conventional type in presentuse.

The foregoing constitute some of the principal objects and advantages ofthe present invention, others of which will become apparent from thefollowing description and the drawings, in

' which Fig. l is a more or less diagrammatic side elevational view of amachine employing a boom embodying the present invention;

Fig. 2 is an enlarged more or less detail view showing the innerconnection for the cables and an equalizer therefor;

Fig. 3 is an enlarged, vertical, sectional view through the boom, theview being taken on the line 3---3 of Fig. 1; and

Fig. 4 is an enlarged, fragmentary, vertical sectional view takenthrough the upper chord of the boom and showing the supports for thecables. I

i For purposes of illustration a single embodiment of the presentinvention will be described herein, it-being recognized, of course, thatmany ,modifications may be made without departing from the intendedscope of the invention.

5 Claims. (Cl. 212-144) Referringnow to the drawings a heavy machine,such as an excavating machine, is illustrated generally at l andincludes a machine base generally indicated at I l. Mounted on this baseis a house or machine cab l2.

The boom forming the subject matter of th present invention isillustrated generally at [3 and as shown is provided with a pair ofhorizontally spaced lower chord members H '(see Figs. 1 and 3), a pairof horizontally spaced upper chord members l and a pair of upwardlyextending end truss members, one of which is shown at H5 in Fig. 1. Thelower and upper chord members l4 and are connectedtogether at theiroutermost end indicated at I1 and throughout their lengths there areprovided intermediate truss members l8. As bestshown in Fig. 3aphirality of cross ties l9 are-provided throughout the length'of thelower chords l4.

The boom 13 is pivotally mounted at its lower inner end as at 2! tobrackets 22 that are mountedon the machine base ll so that the boom 13as a unit is adapted to pivot about these pivot connections 2|.

A pair of cables 23 extend throughout the full length of the upperchords [5 and are attached at one end as at 24 to anchor members 25 thatare fixed to the outermost end of the boom l3. The other end of each ofthe cables 23 is fastened to an arm 26, which arm as shown in Fig. 2 ispivotally mounted at one end as at 21 to a bracket 28 on each of the endtruss members It. shown in solid lines in'Fig. 2 the cables 23 may besecured as at 29 to the free end of the arms 26.

Referring now to Fig. 1 a framework generally indicated at 30 may bemounted on the machine base H and extend upward y to a position abovethe house or machine cab l2. A pair of pulleys, one of which is shown at31 in Fig. 1 may be rotatably mounted at the upper end of the framework30, and a pair of cables 32 may be adapted to operate over the pulleys3!. Each of the cables 32 is secured at one end at 29 (Fig. 2) to thefree end of the arm 26, while the other end of each cable may pass overa drum or Windlass generally indicated at 33 in Fig. 1. This drumorWindlass is supported on the machine cab l2 and v is powered in anysuitablemanner from an enand the other end of the cable passes into themachine cab E2 to a powered Windlass mounted therein. Thus theexcavating shovel 35 may be lowered and raised by means of cable 35passing over the pulley 34. The boom 13 is raised and lowered about itspivot connections 2! by means of cables 32 operating about the poweredwindlass 33.

Referring now to Figs. 3 and 4 the top chord members l5 are anglemembers that are adapted to support assubstantially V-shaped plate3'ithat extends throughout the length of the boom. Spaced throughout thelength of this V-shaped plate 31 are a plurality of saddles 38 disposedbeneath each of the cables 23 and as best shown in Fig. 4 the cables 23rest on these spaced saddles 38. Hold-down plates 39 are -dispose'd atspaced intervals on top of thescables-iitiandrthese hold-down plates 39are clamped downwardly by means of bolt and nut assemblies 40 'so'a-s toloosely engage the cables 23. The cables 23 are adapted to move-:backward forma 1 in a lengthwise direction along theplate 3,! ridingon the saddles t8 beneath the hold-.doWn p1ate-3'9, :but verticalwhipping of the cables 2'3'is prevented by the fact that the cables aresupported throughout their length and are thus prevented from sagging"and also by the fact that-they are held -down'by the hold-down plates39 and -..are thus ,prevented fromjumping out of the saddles .38.

In the structure just described the straight lower chordmembers M areadapted to take the :direct ithrust load ,to beicarried by the boom 3."The :cables 23 serve as isuspension :members for the boom and these10913153 :are-atall timesheld in tension eduring :lowering rand ,raising:oi the beam by the ,relativelyishort cables :3 2 that oper ate aboutthe ,windlass .33. :Each. of the; arms to which :the corresponding shortcable 32 is-zattached serves as an-egualizereformaintainin ithecorresponding cable 23:.atal1 times .in tension. 33y movin the loweringand raising cables 32 to the position shown in broken lines 32d andatztaching them at an intermediate point 29a on the arm 26, aproportionate part of the ,loadrnay be carried by the upper chordmembers15, the Flad-being transmitted bythe arm .26 at its conmection-poi-nt2'1.

As-shown'in Fig.2 itmayrbe desirable to provide ;a hydraulic-or aircylinder generally indizcatedat '41 which is equipped With-a plunger J12that is fastened at its free end tothepivotcon- :nection .29 on theupper end of arm 26. The .rinneriend of the plunger '42 is providedwiththe usual piston 43 operating in the cy-linder e: and theair or"hydraulic fluid is introduced .llltOaCYlllh- .dc.r=,4-| throughsuitable pipe connectionefiri-to a ,tank oraccumulator (not shown)having a fixed III-6581128. Thus as the boom 43 is lowered by lettingrout or len thening the :cables 32 the egualizer cylinder 4 i tends.toimaintainlthe cables :13 in .taut lcondition with a limited and knownload being -carried .by the relatively light members 15,, and thebalance of the suspension load beingcarried by the cables 23.

.Ilclaim:

1. A device of the class described comprising a .base member, ;a boompivotallymounted at one end .to the basecmember and projectin upwardlyand outwardly therefrom, .theboom comprising a lower stiff frame member,a continuous top chord connected at .its outer end to the lower memberand spaced above the lower member ,at its other end,,and truss membersconnecting the lower member and the top chord, a cable attached at oneend to the outer portion of the boom and extending backward throughoutthe length of the boom and terminating at its other end adjacent to theinner end of the top chord, the cable being supported throughout itsentire length by the top chord, a second cable fixed at one end to thelast mentioned terminating end of the first cable and secured at itsother end to the base member.

2. A device of the class described comprising a base member, a boompivotally mounted at one end to Zthe base member and projecting upwardlyand outwardly therefrom, the boom comprisin a lower stiff frame member,a continuous top chord connected at its outer end :to the lower memberand spaced above the lower .member at its other end, and truss membersconnectingthe lower member and the top chord,

.arcableattached atone end to the outer portion of the boom andextending backward throughout the length of the boom and terminating atits other end adjacent to the inner end of the 'top chord, :alongitudinally disposed plate sub- .stantially coextensive with thelength of the :top :chord and mounted on the top chord, the

cable being supported throughout its 'entire length by said plate, asecondcable fixed .at -one end to the last mentioned terminating end :of

the "first cable and secured vat its other end "to ;member extendingfrom the v:free :end .of the 'boom throughout the .length :of the boom,and

i an upper ;member ssecured:.at. one end :to the :free end of .the lower1-thrust;.member;and :disposed above the thrust .member, a supportin:calble including along cable secured to :the boom :ad-

jacent the '.'free endtthereof and extending :along the upper member toa iposition at the opposite end of the boom, 'and a :shorter cablesecured at one end to the last mentioned :end :of :the

"long cable and at the other end to the :base

member, and supporting means 'on the :upper member engaging the longcable and supporting the long cable substantially throughout. itslength.

4. The combination of a basemember, a relatively rigid boom pivoted at'oneendito 'thebase member 'and having aliree and spaced from the basemember, and including a stifi :lower thrust member extending from thefree end of the boom throughout the length of the boom, and an uppermember secured at one end to the free end of the lower thrust .memberand disposed above the thrust member, :a supporting cable including along cable secured to the booma'djacent the free end thereof andextending along the upper member .to a position 'at .the opposite end ofthe boom, an equalizer on the 'boomJclisposed adjacent to 'the uppermember :and adjacent to the pivot endof the boom, :cabl'e'iasteningmeans on the equalizer, the long cable being attached to the cablefastening means, a shorter cable secured'at one end to thecablefastening means and to the base member at'the other end, andsupporting'means on the upper member engaging 'and supporting the longcable substantially throughout its length.

5. The combination of a base member, arelatively rigid boom pivoted atone end to the base member and having a 'free end spaced from the basemember, and including a stifi'lower thrust member extending from thefree end of the boom throughout the length of the boom, and an uppermember secured at one end to the free

